Fix https://issues.apache.org/bugzilla/show_bug.cgi?id=57340
Ensure that Socket and SocketWrapper are only returned to the cache once on socket close (it is possible for multiple threads to call close concurrently).

git-svn-id: https://svn.apache.org/repos/asf/tomcat/trunk@1646304 13f79535-47bb-0310-9956-ffa450edef68